In addition to the following guaranteed sources, the best random locations are:

Quicksilver ingots may be sold by blacksmiths starting at level 18 and general goods merchants starting at level 10.

Quicksilver ore may be randomly found in Falmer loot starting at level 5.

There are a total of 57 veins, 10 ores, and 13 ingots available in the game. The following list only includes notable locations, in particular locations where multiple veins are located near each other and interior areas containing veins or ingots. The Quicksilver Veins category contains a more complete list of places containing single veins, and all exterior ore veins are shown on (map).